FKIE_CVE-2026-90264

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-10-30 13:20
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: btrfs: always wait for ordered extents to avoid OE races [BUG] Syzbot reported a bug that there can be conflicting OEs for the same range: BTRFS critical (device loop4): panic in insert_ordered_extent:264: overlapping ordered extents, existing oe file_offset 16384 num_bytes 430080 flags 0x1089, new oe file_offset 16384 num_bytes 430080 flags 0x80 (errno=-17 Object alrea[ 179.162726][ T6897] BTRFS critical (device loop4): panic in insert_ordered_extent:264: overlapping ordered extents, existing oe file_offset 16384 num_bytes 430080 flags 0x1089, new oe file_offset 16384 num_bytes 430080 flags 0x80 (errno=-17 Object already exists) ------------[ cut here ]------------ kernel BUG at fs/btrfs/ordered-data.c:264! Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 RIP: 0010:btrfs_alloc_ordered_extent+0x943/0xad0 Call Trace: <TASK> cow_file_range+0x744/0x12a0 fallback_to_cow+0x5ea/0xa00 run_delalloc_nocow+0x110c/0x17a0 btrfs_run_delalloc_range+0xbe4/0x1c20 writepage_delalloc+0x104d/0x1ba0 btrfs_writepages+0x1667/0x28b0 do_writepages+0x338/0x560 filemap_fdatawrite_range+0x1f2/0x300 btrfs_fdatawrite_range+0x54/0xf0 btrfs_direct_write+0x6a0/0xc30 btrfs_do_write_iter+0x329/0x790 do_iter_readv_writev+0x624/0x8d0 vfs_writev+0x34c/0x990 __se_sys_pwritev2+0x17a/0x2a0 do_syscall_64+0x174/0x580 entry_SYSCALL_64_after_hwframe+0x77/0x7f </TASK> ---[ end trace 0000000000000000 ]--- [CAUSE] Since commit ff66fe666233 ("btrfs: fix incorrect buffered IO fallback for append direct writes"), if the direct IO finished short, we will revert the isize back to the original one, so that append writes can be respected during the buffered fallback. Normally we rely on lock_and_cleanup_extent_if_need() function during buffered writeback to wait for any existing ordered extents. But that ordered extent waiting only happens if the start_pos is inside the isize. Since we have reverted the isize during failed direct IO, we will not wait for any ordered extents. This means we can have a race where the direct IO OE is still in the tree, finished but not yet removed, then we're inserting the OE for the buffered write, causing the above crash. [FIX] Make the OE wait to be unconditional, to handle the reverted isize situation. And since lock_and_cleanup_extent_if_need() now either lock the extents or return -EAGAIN, also remove the branches that handles no-extent-locked cases, and rename it to remove the "_if_need" suffix. The following micro benchmark shows the runtime difference for btrfs_buffered_write(), doing `xfs_io -f -c "pwrite 0 1m"` workload, all values are the average runtime in nano seconds. function runtime | before | after -----------------------------------+-------------+--------------- lock_and_cleanup_extent_if_need() | 58.2 | 183.0 btrfs_buffered_write() | 2115.6 | 2973.3 The overall runtime of btrfs_buffered_write() is still pretty tiny (still less than 3 micro seconds), I'd say the extra cost is still acceptable. An alternative to fix this problem is to wait ordered extents during iomap_end() where the isize revert is done. But that solution will break nowait requirement, as if a nowait direct IO finished short, we have to wait for the OEs unconditionally or the next append buffered IO can still hit the same problem. So here we have to move the wait cost to buffered write, but at least the code is slightly more streamline.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/043b6fd9706e4335851f317352d2717ad40e6d83
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/58ce50b1802a446d3b26df1b9c58be1ab8913d0e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/aaac9b352f7f53f5d2f7e58e612d67d2a2bf7094
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de8f5cb3cb611f96909797b4b017831f5141cbbe
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ec78575dde998c21be7e0cb2503b5620f34b6255
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fa9f6e1958bb05b8a660d9cf2b6f51dee0077290
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "fa9f6e1958bb05b8a660d9cf2b6f51dee0077290",
              "status": "affected",
              "version": "10b1abc1d0c8ae25c2b9ac465515717c68ffff05",
              "versionType": "git"
            },
            {
              "lessThan": "043b6fd9706e4335851f317352d2717ad40e6d83",
              "status": "affected",
              "version": "097b159d43407b4ea0e5d14ae58a3bbfa5865a24",
              "versionType": "git"
            },
            {
              "lessThan": "de8f5cb3cb611f96909797b4b017831f5141cbbe",
              "status": "affected",
              "version": "ccd5c23122b01de646c80485e2fadac82d1aab62",
              "versionType": "git"
            },
            {
              "lessThan": "58ce50b1802a446d3b26df1b9c58be1ab8913d0e",
              "status": "affected",
              "version": "c3a3d3986719026c85950bfa6f41a251fc46e16f",
              "versionType": "git"
            },
            {
              "lessThan": "aaac9b352f7f53f5d2f7e58e612d67d2a2bf7094",
              "status": "affected",
              "version": "ff66fe6662330226b3f486014c375538d91c44aa",
              "versionType": "git"
            },
            {
              "lessThan": "ec78575dde998c21be7e0cb2503b5620f34b6255",
              "status": "affected",
              "version": "ff66fe6662330226b3f486014c375538d91c44aa",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "4b5875cbb85dbf4d11385eb0a7a589c086d76d42",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "b8df7f486a4617d3096b8fa27148cfa54b1d6a8d",
              "versionType": "git"
            },
            {
              "lessThan": "6.1.191",
              "status": "affected",
              "version": "6.1.178",
              "versionType": "semver"
            },
            {
              "lessThan": "6.6.160",
              "status": "affected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThan": "6.12.114",
              "status": "affected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThan": "6.18.52",
              "status": "affected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThan": "5.16",
              "status": "affected",
              "version": "5.15.212",
              "versionType": "semver"
            },
            {
              "lessThan": "7.2",
              "status": "affected",
              "version": "7.1.4",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/btrfs/file.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.2"
            },
            {
              "lessThan": "7.2",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.191",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.114",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: always wait for ordered extents to avoid OE races\n\n[BUG]\nSyzbot reported a bug that there can be conflicting OEs for the same\nrange:\n\n  BTRFS critical (device loop4): panic in insert_ordered_extent:264: overlapping ordered extents, existing oe file_offset 16384 num_bytes 430080 flags 0x1089, new oe file_offset 16384 num_bytes 430080 flags 0x80 (errno=-17 Object alrea[  179.162726][ T6897] BTRFS critical (device loop4): panic in insert_ordered_extent:264: overlapping ordered extents, existing oe file_offset 16384 num_bytes 430080 flags 0x1089, new oe file_offset 16384 num_bytes 430080 flags 0x80 (errno=-17 Object already exists)\n  ------------[ cut here ]------------\n  kernel BUG at fs/btrfs/ordered-data.c:264!\n  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026\n  RIP: 0010:btrfs_alloc_ordered_extent+0x943/0xad0\n  Call Trace:\n   \u003cTASK\u003e\n   cow_file_range+0x744/0x12a0\n   fallback_to_cow+0x5ea/0xa00\n   run_delalloc_nocow+0x110c/0x17a0\n   btrfs_run_delalloc_range+0xbe4/0x1c20\n   writepage_delalloc+0x104d/0x1ba0\n   btrfs_writepages+0x1667/0x28b0\n   do_writepages+0x338/0x560\n   filemap_fdatawrite_range+0x1f2/0x300\n   btrfs_fdatawrite_range+0x54/0xf0\n   btrfs_direct_write+0x6a0/0xc30\n   btrfs_do_write_iter+0x329/0x790\n   do_iter_readv_writev+0x624/0x8d0\n   vfs_writev+0x34c/0x990\n   __se_sys_pwritev2+0x17a/0x2a0\n   do_syscall_64+0x174/0x580\n   entry_SYSCALL_64_after_hwframe+0x77/0x7f\n   \u003c/TASK\u003e\n  ---[ end trace 0000000000000000 ]---\n\n[CAUSE]\nSince commit ff66fe666233 (\"btrfs: fix incorrect buffered IO fallback\nfor append direct writes\"), if the direct IO finished short, we will\nrevert the isize back to the original one, so that append writes can be\nrespected during the buffered fallback.\n\nNormally we rely on lock_and_cleanup_extent_if_need() function during\nbuffered writeback to wait for any existing ordered extents.\n\nBut that ordered extent waiting only happens if the start_pos is inside\nthe isize.\nSince we have reverted the isize during failed direct IO, we will not\nwait for any ordered extents.\n\nThis means we can have a race where the direct IO OE is still in the\ntree, finished but not yet removed, then we\u0027re inserting the OE for the\nbuffered write, causing the above crash.\n\n[FIX]\nMake the OE wait to be unconditional, to handle the reverted isize\nsituation.\n\nAnd since lock_and_cleanup_extent_if_need() now either lock the\nextents or return -EAGAIN, also remove the branches that handles\nno-extent-locked cases, and rename it to remove the \"_if_need\" suffix.\n\nThe following micro benchmark shows the runtime difference for\nbtrfs_buffered_write(), doing `xfs_io -f -c \"pwrite 0 1m\"` workload,\nall values are the average runtime in nano seconds.\n\n      function runtime              |   before    |     after\n -----------------------------------+-------------+---------------\n lock_and_cleanup_extent_if_need()  |     58.2    |    183.0\n btrfs_buffered_write()             |   2115.6    |   2973.3\n\nThe overall runtime of btrfs_buffered_write() is still pretty\ntiny (still less than 3 micro seconds), I\u0027d say the extra cost is still\nacceptable.\n\nAn alternative to fix this problem is to wait ordered extents during\niomap_end() where the isize revert is done.\n\nBut that solution will break nowait requirement, as if a nowait direct\nIO finished short, we have to wait for the OEs unconditionally or the\nnext append buffered IO can still hit the same problem.\n\nSo here we have to move the wait cost to buffered write, but at least\nthe code is slightly more streamline."
    }
  ],
  "id": "CVE-2026-90264",
  "lastModified": "2026-10-30T13:20:48.187",
  "metrics": {},
  "published": "2026-09-17T17:17:22.853",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/043b6fd9706e4335851f317352d2717ad40e6d83"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/58ce50b1802a446d3b26df1b9c58be1ab8913d0e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/aaac9b352f7f53f5d2f7e58e612d67d2a2bf7094"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/de8f5cb3cb611f96909797b4b017831f5141cbbe"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ec78575dde998c21be7e0cb2503b5620f34b6255"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fa9f6e1958bb05b8a660d9cf2b6f51dee0077290"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.